Process for the reduction of iron ores or the like in the production of pig iron in the blast furnace

ABSTRACT

An improvement in a process for the reduction of an iron ore, sinter or other such starting materials in a blast furnace in which as the reducing agent there is employed a water in oil emulsion, the water content being between 3 and 15% by volume. The water in oil emulsion is introduced into the tuyeres of the blast furnace through tubular lances terminating therein, the tubular lances having an aperture between 4 and 6 mm in diameter.

United States Patent Heynert et al.

[ Dec. 24, 1974 PROCESS FOR THE REDUCTION OF IRON ORES OR THE LIKE INTHE PRODUCTION OF PIG IRON IN THE BLAST FURNACE Inventors: GerhardHeynert, Mulheim;

Karl-Heinz Peters, Duisburg-Hamborn, both of Germany AugustThyssen-I-Iutte Aktiengesellschaft, Duisburg-Hamborn, Germany Filed:Apr. 27, 1972 Appl. N0.: 248,137

Assignee:

[30] Foreign Application Priority Data Apr. 30, 1971 Germany 2121241 US.Cl. 75/42 Int. Cl C21b 5/00 Field of Search 75/41, 42; 44/51 [56]References Cited] UNITED STATES PATENTS 2,152,196 3/1939 Kokatnur 44/512,175,517 10/1939 Ditto 75/41 Primary Examiner-L. Dewayne RutledgeAssistant Examiner-M. J. Andrews Attorney, Agent, or Firm-Burgess,Dinklage & Sprung [57] ABSTRACT An improvement in a process for thereduction of an iron ore, sinter or other such starting materials in ablast furnace in which as the reducing agent there is employed a waterin oil emulsion, the water content being between 3 and 15% by volume.The water in oil emulsion is introduced into the tuyeres of the blastfurnace through tubular lances terminating therein, the tubular lanceshaving an aperture between 4 and 6 mm in diameter.

14 Claims, l Drawing Figure PROCESS FOR THE REDUCTION OF IRON ORES ORTHE LIKE IN THE PRODUCTION OF PIG IRON IN THE BLAST FURNACE BACKGROUNDOF THE INVENTION 1. Field of the Invention The invention relates to aprocess for the reduction of iron ores, sinters or other such startingmaterials in the blast furnace, in which coke and oil are used asreducing agents.

2. Discussion of the Prior Art In the classical processes of pig ironproduction in the blast furnace, the reduction of the iron oxides is performed by means of high-quality carbonaceous reducing agents such ascoke or wood charcoal. Years of efforts to achieve an increase ofefficiency combined with a reduction of the cost of pig iron productionin the blast furnace have led to the replacement of some of theexpensive and bulky metallurgical coke with oil or gas,.such as naturalgas.

The prior art has suggested replacing the more expensive coke in theblast furnace in part with oil. This proposal resulted in use of 60 to80 kg of oil per ton of pig iron, depending on operating conditions. Anyfurther increase in the proportion of oil is blocked by the fact that asthe amount of oil increases the size of the oil drops increases and thusthere is not enough time for the gasification of the oil in the reactionchamber (area between the lance orifice and the coke face). The resultis that the ungasified oil drops, upon encountering the hot coke, formcarbon black whichcan create trouble in operation.

The formation of carbon black can be restrained by the use of commercialburner designs, such as pressurespray burners, steam-spray burners orcompressed-air spray burners, which under certain circumstances permit asufficiently fine atomization of the oil. Experiments with these typesof burners, however, have shown that the installation of these systemsentails appreciable expense. Furthermore, difficulties arise in theiroperation, and the systems are not entirely reliable.

It has been proposed to use emulsions of water in oil from combustion.Such emulsions contain at least 25 percent by volume water and up to 70percent by volume to provide for the desired atomization of the oil.Such emulsions, however, are undesirable because the droplet size isstill not as small as desired. Specifically, the droplet size of the oilin water emulsion is about 50 microns in diameter whereas a smallersize, say, 30 microns or less in diameter is desired. Additionally,because of the large proportion of water in the emulsion more reducingagent was required to provide the desired oil level in the blastfurnace. Furthermore, use of large amounts of water in the water-in-oilemulsion provides an undesirably high heat loss factor.

Pursuant to the present invention, such difficulties are prevented.Thus, it is an object of the invention to provide a considerablediminution of the proportion of expensive an bulky coke used in iron orereduction. It is another object of the invention to prevent theundesirable formation of carbon black, and to permit the injection oflarge amounts of oil by means of the simple tubular lances whosepracticality has long been established.

SUMMARY OF THE INVENTION Broadly, this invention contemplates animprovement in a process for the reduction of iron ore, sinters or othersuch starting materials wherein at least a portion of the reducing agentis an oil, the improvement which comprises utilizing as such oil awater-in-oil emulsion having a water content between 3 and 15 percent byvolume.

This invention contemplates, in a desirable embodiment, utilization of awater-in-oil emulsion having a water content between 3 and 15 percent byvolume, preferably between 3 and 10 percent by volume. The saidwaterin-oil emulsion is introduced through tubular lances terminating inthe tuyeres of the blast furnace, said tubular lances having an aperturebetween 4 and 6 mm in diameter. In such particularly desirableembodiment the quantity of oil employed is between and 200 kilograms ofoil per metric ton of pig iron, preferably between and kilograms of oilper metric ton of pig iron.

In accordance with another highly desirable embodiment of the inventionthe reduction of the iron ore, sinter or other starting material in theblast furnace is accomplished by passing the water-in-oil emulsionthrough the aforesaid tubular lances terminating in the tuyeres of theblast furnace and conducting the reduction in said blast furnace at ablast velocity of between 100 and 300 m/sec. at a blast temperature ofbetween I,OO0 and I,400C.

DISCUSSION OF PREFERRED EMBODIMENTS The objects of the inventionoutlined above are achieved through use of an oil, distillate orresiduum, especially heavy oil, residual oil or fuel oil, in the form ofwaterin-oil emulsion having a very low water content. The water contentof the water-in-oil emulsion is at least 3 percent by volume. In nocase, however, must the water content exceed 15 percent by volume. Thisemulsion is injected, in accordance with the invention, through tubularlances which terminate in the tuyeres of the blast furnace. Watercontents of between 3 and 10 percent by volume are preferred. When suchsmall portions of water are used, micro explosions are obtained whichare caused by the vaporization of tiny water droplets enveloped by theoil phase, resulting in an extremely fine vaporization of the oil.Accordingly, it is surprising that, in the process of the invention,water-in-oil emulsions having a very low water content, amounting toonly a few percent of water, can be so finely atomized in the blastfurnace that oil particles ranging from virtually 0 to 30 microns areformed. This oil particle size is achieved when the water-in-oilemulsion is introduced into the tuyeres of the blast furnace at a blastvelocity of 100 to 300 m/sec and a blast temperature of 800 to l,400C,preferably l,O00 to 1,400C.

Through use of such water-in-oil emulsions a large portion of theexpensive coke otherwise needed for the reduction in the blast furnacecan be replaced by emulsion such that at least 90 kg of oil is injectedinto the blast furnace for each ton of pig iron.

In particular, the process of the present invention can be performed byinjecting oil in quantities of 90 to 200 kg of oil per metric ton of pigiron, 100 to 160 kg of oil per ton of pig iron being perferred. In thismanner considerable amounts of coke can be saved, the saving amountingto as much as 30 percent. Furthermore, by using tubular lancesterminating in the tuyeres of the blast furnace, the oil feed is mademechanically very simple, avoiding the difficulties involved in complexatomizers. The aperture of the lances is optimumly between 4 and 6 mm.in diameter.

Normally, the reducing agent of the invention can be injected into thetuyere at a pressure that is l to 2 atmospheres higher than the pressureof the hot blast. It is advantageous, however, to increase this pressureto 10 to 60 atmospheres, for example. Special advantages are achievedwhen the additional pressure amounts to 40 to 50 atmospheres. Theproportion of extremely fine oil droplets is greatly increased by theuse of elevated pressure.

The water-in-oil emulsions can be prepared in a conventional manner byhomogenizers, e.g., colloid mills.

It is especially advantageous to use a high-pressure homogenizer but toprevent heat losses in the blast furnace only as much water is added inaccordance with the invention as is needed barely to assure sufficientatomization of the oil in the reaction chamber.

It may be desirable, under certain circumstances, as for example incases in which the emulsions are to be stocked to add emulsifiers tothem. Examples of suitable emulsifiers are alcali salts of fatty acids.

In order to more fully illustrate the nature of the invention in themanner of practicing the same, the following Example is presented.

EXAMPLE A heavy oil was made into a water-in-oil emulsion in ahigh-pressure homogenizer using water in a volume ratio of 5: 95. 150 kgof oil per metric ton of'pig iron, in the form of the emulsion, wasinjected through lances having an aperture of 5 mm diameter into thetuyeres of a blast furnace having a hearth diameter of 9.5 m, at apressure of 12 atmospheres.

The blast furnace was operated with a burden consisting of 70 wt-percentsinter and 30 wt-percent lump ore plus fluxes. The blast velocityamounted to 200 m/s and the blast temperature was l,l00C. No carbonblack formation or any other trouble was encountered. The coke chargeamounted to 370 kg per ton of pig iron. Previously the same furnace withthe same burden required a coke charge of 450 kg and 60 to 80 kg ofheavy heating oil per ton of pig iron.

These figures show that more than twice the amount of oil and about 15percent less coke can be used, while the smelting of the iron ore takesplace much more uniformly and under better control. This contributes,also, to longer furnace'life. Furthermore, less coke slag is producedand a qualitatively better blast-furnace gas is obtained.

By the process of theinvention, therefore, in contrast to the prior artprocedures, it is possible to inject more than twice the amount of oilinto the blast furnace without causing the undesirable formation ofcarbon black. The lower proportion of coke made possible by the use ofoil makes it possible to charge the furnace with correspondingly moreore, so that the production of pig iron can be considerably increased.Furthermore, the lower proportion of coke results in correspondinglyless slag, and the gas has a higher heat value.

The drawing shows in a horizontal section a tuyere l of a blast furnacehaving a centrally arranged tuyere pipe 2. From the left side a tubularlance 3 is introduced under an acute angle 4 to the middle axis 5 of thetuyere pipe 2.

Through tuyere pipe 2 blast gas is blown into the blast-furnaceindicated by numeral 6 and through tubular lance 3 water-in-oil emulsionis introduced into the interior of the tuyere pipe 2.

The terms and expressions used herein have been used as terms ofdescription and not of limitation as there is no intention, in the useof such terms and descriptions, of excluding any equivalents, orportions thereof, as many modifications and departures will becomeobvious to one skilled in the art. For instance, the method in which thewater-in-oil emulsion is injected into the tuyeres of the blast furnacecan be modified.

Additionally, while the present invention has been illustrated inparticular in reducing sinter and lump iron ore, it will be apparentthat other blast furnace starting materials can be employed. Similarly,other hydrocarbonaceous oils can be employed as the composition of theoil is not especially critical. Oils generally suitable for blastfurnace operations can be used in the waterin-oil emulsions providedpursuant to the process of the present invention.

What is claimed is:

1. In a process for the reduction of an iron ore, sinter or other suchstarting material in a blast furnace in which at least a portion of thereducing agent comprises an oil, the improvement comprising introducingsaid oil into the blast furnace in the form of a water-inoil emulsionhaving a water content between 3 and 15 percent by volume, said emusionbeing introduced in the tuyeres of the blast furnace, the amount of oilcharged into the blast furnace being at least kg of oil per metric tonof pig iron in the blast furnace.

2. A process according to claim 1 wherein the water content of thewater-in-oil emulsion is between 3 and 10 percent by volume.

3. A process according to claim 1 wherein the oil droplets have adiameter of less than 30 microns.

4. A process according to claim ll wherein the waterin-oil emulsion isintroduced into the tuyeres of the blast furnace at a blast velocity ofto 300 m/sec. at a blast temperature of 800 to l,400C.

5. A process according to claim 4 wherein the blast temperature isbetween 1,000 and l,4009C.

6. A process according to claim 1 wherein between 90 and 200 kilogramsof oil are charged into said blast furnace per metric ton of pig iron.

7. A process according to claim 6 wherein between 100 and kilograms ofoil per metric ton of pig iron are charged into said blast furnace.

8. A process according to claim 1 wherein the waterin-oil emulsion isunder a pressure of between 10 and 60 atmospheres.

9. A process according to claim 8 wherein the waterin-oil emulsion isunder a pressure of between 40 and 50 atmospheres.

10. A process according to claim 1 wherein the water-in-oil emulsioncontains an emulsifier.

iii. A process according to claim ll wherein the oil is a heavy oil andthe charge to the blast furnace comprises a mixture of sinter and lumpiron ore containing fluxes said mixture containing a major amount ofsaid sinter.

12. A process according to claim 1 wherein at least 90 kilograms of oilper metric ton of pig iron is charged into the blast furnace.

13. A process according to claim 12 wherein between 90 and 200 kilogramsof oil are charged into said blast furnace per metric ton of pig iron.

114. A process according to claim 13 wherein between 100 and 160kilograms of oil per metric ton of pig iron are charged into said blastfurnace.

)k z}: k i:

1. IN A PROCESS FOR THE REDUCTION OF AN IRON ORE, SINTER OR OTHER SUCHSTARTING MATERIAL IN A BLAST FURNACE IN WHICH AT LEAST A PORTION OF THEREDUCING AGENT COMPRISES AN OIL, THE IMPROVEMENT COMPRISING INTRODUCINGSAID OIL INTO THE BLAST FURNACE IN THE FORM OF A WATER-IN-OIL EMULSIONHAVING A WATER CONTENT BETWEEN 3 AND 15 PERCENT BY VOLUME, SAID EMUSIONBEING INTRODUCED IN THE TUYERES OF THE BLAST FURNACE, THE AMOUNT OF OILCHARGED INTO THE BLAST FURNACE BEING AT LEAST 90 KG OF OIL PER METRICTON OF PIG IRON IN THE BLAST FURNACE.
 2. A process according to claim 1wherein the water content of the water-in-oil emulsion is between 3 and10 percent by volume.
 3. A process according to claim 1 wherein the oildroplets have a diameter of less than 30 microns.
 4. A process accordingto claim 1 wherein the water-in-oil emulsion is introduced into thetuyeres of the blast furnace at a blast velocity of 100 to 300 m/sec. ata blast temperature of 800* to 1,400C.
 5. A process according to claim 4wherein the blast temperature is between 1,000* and 1,400C.
 6. A processaccording to claim 1 wherein between 90 and 200 kilograms of oil arecharged into said blast furnace per metric ton of pig iron.
 7. A processaccording to claim 6 wherein between 100 and 160 kilograms of oil permetric ton of pig iron are charged into said blast furnace.
 8. A processaccording to claim 1 wherein the water-in-oil emulsion is under apressure of between 10 and 60 atmospheres.
 9. A process according toclaim 8 wherein the water-in-oil emulsion is under a pressure of between40 and 50 atmospheres.
 10. A process according to claim 1 wherein thewater-in-oil emulsion contains an emulsifier.
 11. A process according toclaim 1 wherein the oil is a heavy oil and the charge to the blastfurnace comprises a mixture of sinter and lump iron ore containingfluxes said mixture containing a major amount of said sinter.
 12. Aprocess according to claim 1 wherein at least 90 kilograms of oil permetric ton of pig iron is charged into the blast furnace.
 13. A processaccording to claim 12 wherein between 90 and 200 kilograms of oil arecharged into said blast furnace per metric ton of pig iron.
 14. Aprocess according to claim 13 wherein between 100 and 160 kilograms ofoil per metric ton of pig iron are charged into said blast furnace.